1. Field of the Invention
The invention relates to alarms and more specifically to alarms for warning an operator of malfunctions in craft guidance systems employing variable-angle control surfaces.
2. Description of the Prior Art
Marine vessels and aircraft frequently employ complex mechanisms to actuate control surfaces such as rudders, elevators, or ailerons.
Marine vessels, for example, frequently employ electrohydraulic systems to actuate the rudder in response to order signals generated by positioning of the helm. Helm angle indicators and rudder angle indicators are often provided on the bridge so as to enable the pilot to compare these values, but such indicators are not conducive to constant surveillance or early warning in case of malfunction. Furthermore, because of the inevitable lag between helm positioning and rudder response, it is difficult to determine when such lag is approaching an unacceptable value. During critical maneuvers, when the occurrence of a malfunction would be the most dangerous, manual observation of the two indicators would be least likely.